The Australian Transport Safety Bureau on Thursday released its final report into the YM Efficiency incident in 2018, which notes more than a dozen containers remain unaccounted for after debris washed ashore along the Hunter's coast.

The YM Efficiency lost 81 containers around midnight on June 1 in 2018 as it chugged into gale-force winds and rough seas off Newcastle after rolling heavily.

The loss has been at the centre of an ongoing dispute over who should pay for the clean-up.

The watchdog found that "the forces generated during the sudden, heavy rolling placed excessive stresses on containers stowed aft of the ship's accommodation", leading to containers and parts of the lashing system failing and beginning the fall.

"All potential causes for the sudden rolling were investigated, such as the possibility of an abnormal wave, but there was insufficient evidence to establish a definitive cause," the report states.

The condition of lashing equipment was not a factor, the report found, but the weight and distribution of containers in the bays were "such that calculated forces exceeded allowable force limits as defined in the ship's Cargo Securing Manual".

The report notes that operator Yang Ming, who had another ship arrested in Sydney Harbour at the weekend as part of a bid to make them pay for clean-up of the lost containers, has taken measures including requiring checks of lashing forces and training ships' officers in use of the computer system.

Australian Transport Safety Bureau chief commissioner Greg Hood said the investigation found the stowage arrangement was not checked for compliance during the cargo planning process.

"This left sole responsibility for compliance with the ship's officers, with limited options to resolve deficiencies at a late stage in the process without unduly impacting operations," Mr Hood said.

Mr Hood said the incident highlighted the need for effective container stowage planning, noting that the failure to check loads before embarking "left sole responsibility for compliance with the ship's officers, with limited options to resolve deficiencies at a late stage in the process without unduly impacting operations".

"Notwithstanding the efficiency of computerised loading systems, the scale and pace of modern container ship operations puts significant pressure on ship's officers to check and amend or approve proposed stowage plans at a late stage," Mr Hood said.

"Weather forecasting, routing and good navigational practices in adverse weather all play a part in minimising the risk of injuries to crew and damage to ship, cargo and environment."

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